1. Field of the Invention (Technical Field)
The present invention relates to an artificial heart-lung apparatus including an artificial lung or oxygenator, and a pump, and more particularly an undulation pump with a precessional movement.
2. Description of Related Art
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to recent publication dates certain publications are not to be considered as prior art vis-à-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
An artificial heart-lung machine is often necessary for performing heart surgery, especially open-heart surgery. A conventional heart-lung machine includes a pump that transports the blood of a patient in an extracorporeal circuit through flexible tubing to an artificial lung unit for oxygenation of the blood and a heat exchanger unit for maintaining the blood at a predetermined temperature. One of the goals in designing a heart-lung machine is to minimize the circuit priming volume. A low priming volume is advantageous for minimizing dilution of the patient's blood, which often aids in patient recovery. Furthermore, a low priming volume may decrease the amount of transfusion required and may reduce the amount of medication that is needed following surgery.
Much medical research has been devoted to minimizing the priming volume of heart-lung machines. However, heart-lung machines currently in use or under development consist of a large artificial lung and pumping system which are located outside the vicinity of the patient's surgical area and must be operated by a perfusionist. At present heart-lung machines are connected to a patient by long tubes that transport blood between the patient and the machine. The size of the machine and the distance from the patient are obstacles to reducing the priming volume of heart-lung machines. Another problem with heart-lung machines is that they are large and occupy an inefficient amount of space in operating rooms.
One potential solution is to construct a smaller heart-lung machine equipped with a small centrifugal pump that can be used in proximity to the surgical area. However, centrifugal pumps have a cone shape with a drive unit at the bottom, an inlet port that opens in the direction of the axis, and an outlet port that opens in the direction of the circle. The shape of the centrifugal pump makes it impossible to construct an integrated unit in which the pump, drive and lung units are directly connected in series, and thus makes it difficult to design a heart-lung machine which is small enough to be used near the patient's surgical area.
There is thus a need for a heart-lung machine that is both robust and compact, such that it can be positioned immediately adjacent the patient. There is further a need for a heart-lung machine in which the pump, drive and lung units are directly connected in series, thereby minimizing the size of the machine.